| Proximity to Crops and Residential Exposure to Agricultural Herbicides in Iowa Mary H. Ward,1 Jay Lubin,1 James Giglierano,2 Joanne
S. Colt,1 Calvin Wolter,2 Nural Bekiroglu,1,3 David
Camann,4 Patricia Hartge,1 and John R. Nuckols5 1Division of Cancer Epidemiology and Genetics, National Cancer Institute,
National Institutes of Health, Department of Health and Human Services, Bethesda,
Maryland, USA; 2Iowa Geological Survey, Iowa City, Iowa, USA; 3Department
of Biostatistics, Marmara University Medical School, Istanbul, Turkey; 4Southwest
Research Institute, San Antonio, Texas, USA; 5Department of Environmental
and Radiological Health Sciences, Colorado State University, Fort Collins,
Colorado, USA Abstract
Rural residents can be exposed to agricultural pesticides through the proximity of their homes to crop fields. Previously, we developed a method to create historical crop maps using a geographic information system. The aim of the present study was to determine whether crop maps are useful for predicting levels of crop herbicides in carpet dust samples from residences. From homes of participants in a case-control study of non-Hodgkin lymphoma in Iowa (1998-2000) , we collected vacuum cleaner dust and measured 14 herbicides with high use on corn and soybeans in Iowa. Of 112 homes, 58% of residences had crops within 500 m of their home, an intermediate distance for primary drift from aerial and ground applications. Detection rates for herbicides ranged from 0% for metribuzin and cyanazine to 95% for 2,4-dichlorophenoxyacetic acid. Six herbicides used almost exclusively in agriculture were detected in 28% of homes. Detections and concentrations were highest in homes with an active farmer. Increasing acreage of corn and soybean fields within 750 m of homes was associated with significantly elevated odds of detecting agricultural herbicides compared with homes with no crops within 750 m (adjusted odds ratio per 10 acres = 1.06 ; 95% confidence interval, 1.02-1.11) . Herbicide concentrations also increased significantly with increasing acreage within 750 m. We evaluated the distance of crop fields from the home at < 100, 101-250, 251-500, and 501-750 m. Including the crop buffer distance parameters in the model did not significantly improve the fit compared with a model with total acres within 750 m. Our results indicate that crop maps may be a useful method for estimating levels of herbicides in homes from nearby crop fields. Key words: agriculture, exposure assessment, geographic information systems, herbicides, pesticides. Environ Health Perspect 114: 893-897 (2006) . doi:10.1289/ehp.8770 available via http://dx.doi.org/ [Online 2 February 2006]
Address correspondence to M.H. Ward, Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 6120 Executive Blvd., EPS 8104, Bethesda, MD 20892 USA. Telephone: (301) 435-4713. Fax: (301) 402-1819. E-mail: wardm@mail.nih.gov We thank P. Riggs of Colorado State University for his contribution to the review of the analyses. Support for data collection was provided by National Cancer Institute (NCI) grant N01-PC-67008. This research was also supported by the Intramural Research Program of the National Institutes of Health, NCI. J.R.N.’s time was supported in part by research grant R01 CA92683 from the NCI and by an intergovernmental personnel agreement between the NCI Occupational and Environmental Epidemiology Branch and Colorado State University. The authors declare they have no competing financial interests. Received 25 October 2005 ; accepted 2 February 2006. The full version of this article is available for free in HTML or PDF formats. |
